The present invention relates to a key entry and translation arrangement useful for small size data processing units such as electronic desk-top calculators, electronic cash registers, point of sales units, etc.
In placing input information from a keyboard into one of arithmetic registers, according to the prior art approach, the respective keys of the keyboard are supplied with corresponding key stroke signals or time-shared key interrogate signals and key signals originated in response to depressions of desired keys are processed and translated into unique code signals in a key input circuit which is clearly distinct from a central processor unit (CPU). Then, the thus obtained code signals representative of the selected keys enter into the CPU through an input buffer. This approach is well know in the calculator art as disclosed in greater detail in U.S. Pat. No. 3,715,746, for example.
There are problems associated with the above discussed technique, however, which can not provide a substantial reduction in the chip size of a large scale integrated circuit (LSI) for the reason that the key input circuit set forth above needs a large number of circuit components.